High-potential insulator.



S. S. SONNEBOHN.

HIGH PTENTIAL INSULATR.

APPLICATION FILED DEC.9, i915- 1,230,610. Patentedlune 19, 1917,

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SOL. `S. SONNEBORN, OF BROOKLYN, NEW YORK.

HIGH-POTENTIAL INSULATOR.

T0 all whom t may concern:

Be it known that I, SOL. S. SoNNEoRN, a citizen of the United States,and a resident of Brooklyn,`countyof Kings, and State of New York, haveinvented certain new and useful Improvements in High-PotentialInsulators, set forth in the following specification.

This invention relates to high-potential insulators of the condensertype, employed as bushings for insulating transformer leads and the likefrom what is usually a grounded, perforated barrier of conductingmaterial through which the conducting lead must emerge and from which itmust be insulated.

The object of the invention is to form an insulator of as simple,compact and economical construction as possible, and which providesprotective features against high-frequency, high-potential oscillations,due to abnormal line surges as well as embodying an efficient design forthe normal voltages which it is expected to sustain. v

To these ends an important feature of the invention is to provide forrelief without danger of puncture from abnormal stress produced byhigh-frequency oscillations, while, at the same time, employing featuressuch as dielectric configuration conforming to the flow lines ofdielectric stress between terminals, to the end that the full dielectricvalue of the air may be employed. The above and more detailed objects ofthe invention will more fully be understood by reference to theembodiment of the invention described for illustrative purposes in thefollowing specification and shown in the accompanying drawings, whichform a part hereof, in which like characters designate correspondingparts in the figures and in which Figure 1 is a sectional elevationthrough an illustrative embodiment and Fig. 2 is a bottom plan of amodified sheath skirt.

A indicates one embodiment illustrating the practice of my invention inthe form of `a highpotential insulating bushing of the type adapted topass through a barrier of,

conducting, usually grounded, metal such as the transformer casing B. Inthis type of insulator the maximum stress occurs between the lead 1 andthe casing 2. In practicing my invention I contemplate the usefulemployment of the insuating fluid 2, which is the oil customarilyfilling a transformer case.

Specification of Letters Patent. Patented Jung 19, 191W.

Application filed December 9, 1916. Serial No. 135,922.

The insulator illustrated in Fig. 1 co1n prises a molded body 3 ofsuitable insulating material, which may be molded in thc plastic state,afterward to harden and solidify. In its finished form all the partsshown in Fig. 1 may be considered in their finished embodiment ascylindrical, such term being used in its broad sense, meaning thatsurfaces are surfaces of revolution. The axis of the various parts isthat of the lead 1, which is shown in the form of a bolt with anysuitable form of connectors such as nuts 4l.

A plurality of cylindrical metal sheaths 5 and 6, each having anoutwardly flaring skirt 7 with an upturned marginal lip 8 on itsouterend and an outwardly flaring skirt 9 on its inner end, areco-axially supported in a suitable mold and the plastic, insulating material 3 is forced about these shells and into the mold, a suitable coreforming an axial perforation for the bolt 1, which also can be moldedin. The configuration of the mold should be such as to form an outwardlyfiaring petticoat 410 about the outer face of each skirt 7. Cylindricalpartitions 11 and 12 of insulating material of cylindrical formalternate with the cylindrical sheaths 5 and 6. The stem oftheinsulator, adapted to pass f through the barrier B, may be protected bya sheet metal bushing 13.

The contour of the outwardly Haring metal skirts 7 is such as to reducethe local dielectric stress between the conductor 1 and the casing B,and the exposed surfaces of petticoats l0 of insulating material aredesigned to conform as nearly as practicable with the flow lines ofdielectric stress. Inasmuch as the surrounding dielectric about theouter portion of the insulator A is air, the distance from the exposedend of the lead 1 to the casing B is greater than the distance from theinner end of the lead 1 from the casing B, because it is proposed thatthe inner end of the lead 1 is to be immersed in oil. ThisV likewise istrue for the outwardly flaring skirts 9 which may be located nearer tothe casing B than can the skirts 7. The proportioning and spacing in thevarious parts is preferably such that a iiash-over or arc-over from thelead 1 to the casing B will never take place wholly by creepage orwholly through the air. A breakdown due to abnormal high frequencyvoltage will take place from one or the other or both of the out-flaringmetal conducting skirts 9, immersed in the oil 2, the discharge takingplace through the oil 2 to the casing B so that the dielectric mediumthrough udii'cl the destructive discharge takes place will beself-healing and quenching, as is the nature of oil. At the same time,stressthroughout the body of the insulators solid dielectric is welldistributed and relieved from intensity at any one spot by theseparating sheaths serving as condenser plates. In this way the puncturepotential of the bushing is increased substantially in proportion to itsdiameter, which is impossible Aby the use of a single layer ofinsulating material.

It is oi course to be understood .that .the exact number of petticoatsshown in the embodiment illustrated is not a feature .oi the invention.Likewise, the invention is Lnot limited to the providing of eachcylindrical metal sheath with an outwardly flaring skirt on each end, asa measure of advantage rmay be obtained by` such provisions on but lonesheath. Likewise, the number of sheaths is not limited to that shownanddescribed.

If desired, the breakdown tendency between the casing B and the 4skirts9 maybe increased by forming the Vskirts 9 at their margins starshapedor with any kind of easily discharging points such as the starshapedskirt 90 as shown in Fig. 2.

It is also .to be understood `that such accessories as packing gaskets2O anda finetal cap 2l may be employed. y

Vhat I claim and whatI I kdesire to secure b y United States LettersPatent is:

l. A high-potential insulating bushing of the condenser type comprisinga plurality of cylindrical partitions of insulating material; and one ormore coaxial cylindrical metal sheaths alternating' with saidpartitions, each said metal sheath being flared at each end intoanoutwardly extending skirt.

2. A high-potential insulating bushing of the condenser type comprisinga plurality of cylindrical partitions of insulating material 3 one ormore of said partitions having at one end an outwardly `flaringpetticoat; and one or more coaxial cylindrical met-al sheathsalternating with said partitions, each said metal `sheath being iiaredateach end into an outwardly extending skirt, the skirt at one endlforming a one-face-covering lor one ol said petticoats.

3. A high-potential insulating bushing ot the Vcondenser ktypecomprising a vcomposite of molded insulating material and embedded metalsheaths rvforming alternating cylindrical partitions of insulation landcylindrical .metal sheaths, 4one of said metal sheaths vhavingan-outwardly flaring skirt at each end.

4L. A highpotential transformer bushing ot the condenser type comprisingalternating coaxial layers of insulation and one or more metalsheaths,one oi' said metal sheaths being outwardly flared at the end ot' theinsulator adapted to -be inserted into the transformer.

In witness whereof I have signed my name to this specification, .this8th vday of December, 1916.

SOL. S. SONNEBORN.

Copies of this patent may be obtained -for ve .cents each, by addressingthe Commissioner of Patents, Washington, D. C.

